Frequently asked questions
The most common questions about Solspejder: how accurate it is, what it can and cannot do, where the data comes from, and how to plan around the sun. For the details behind the method, read About Solspejder.
How accurate is the sun and shade calculation?
The sun's position is calculated astronomically with SunCalc and is very accurate, down to the minute. The shadows depend on the building heights. In the centres of Copenhagen, Aarhus, Odense and Aalborg these are measured from Denmark's national elevation model and are typically within a couple of metres. Outside those areas we estimate from the building type, where the error can be larger.
Treat the result as an informed guess, not a guarantee. Trees, parasols and terrain are not included.
Does Solspejder work for apartments and balconies?
Yes. Pick the floor on the point card and Solspejder assumes you are that high above street level (3.1 metres per floor). A building can only shade you if it rises above you, so a balcony typically gets sun earlier in the morning and later in the evening than the pavement below. We don't know exactly where on the facade the balcony sits, so the figure applies to the address as a whole.
How often is the sun angle updated?
As long as the page is open and visible, it automatically follows the real clock and updates every 30 seconds. Dragging the timeline or picking another date freezes the time on your choice; tap "Jump to now" to return to the live view.
Does Solspejder account for trees, parasols and fences?
No. The model only knows buildings from OpenStreetMap. Trees, hedges, parasols, fences, bridges and vehicles do not cast shadows in the calculation.
Why does it show sun when it is overcast?
"In sun" means the sun is not blocked by a building at that time, not that the sky is clear. Cloud cover is shown separately as weather, fetched from Open-Meteo.
Where does the building data come from?
Building footprints come from OpenStreetMap via the Overpass API. Heights are measured from Denmark's national elevation model in the centres of Copenhagen, Aarhus, Odense and Aalborg; elsewhere OpenStreetMap's own heights or a type-based estimate are used. The sun's position comes from SunCalc, and weather, wind and UV come from Open-Meteo. The map is OpenFreeMap tiles shown with MapLibre GL. Read more on the About page.
Does Solspejder work across all of Denmark?
Yes. You can click any point on the map or search for an address or place name anywhere in Denmark, on both mobile and computer. There are also shortcuts to the largest cities.
Can I see sun and shade for another day or a future time?
Yes. Sun and shade can be calculated for any date, because it is pure astronomy and geometry. Weather, wind and UV are only available 7 days ahead, since they come from a forecast.
What does shelter mean, and how is it calculated?
Shelter is a measure of whether buildings screen your point from the current wind. Solspejder fetches wind direction and speed from Open-Meteo and looks at buildings in a sector towards the wind. The largest angle a building spans decides the verdict: sheltered, some shelter or exposed.
It is a geometric approximation that does not model turbulence or wind between buildings.
Does Solspejder cost anything, and do I need an account?
No. Solspejder is free, needs no account and no login. All calculations happen in your browser, and there are no tracking cookies and no ads.
Can I share a link to a specific place and time?
Yes. Select a point, open the three-dot menu on the point card, and tap Share. That copies a link to exactly the place and time you're looking at. The recipient sees exactly the same place, day and time.
A building or shadow looks wrong, what do I do?
This is usually down to missing or inaccurate data in OpenStreetMap. You can correct and add buildings yourself at openstreetmap.org, and the corrections flow through to Solspejder automatically after a while.